Organic light emitting diode (OLED) is one of the current focuses in the field of display research. Compared with a liquid crystal display (LCD), an OLED display has the advantages of low energy consumption, low production cost, self-luminescence, wide viewing angle, and fast response speed. Currently, OLED displays have begun to replace traditional LCD displays in various display fields such as mobile phones, personal digital assistants (PDAs), and digital cameras.
Unlike a pixel unit in an LCD display that uses a stable voltage to control luminance, an OLED in an OLED display is driven by current and requires a steady current to control light emission. Therefore, when the OLED operates, there may be a large current. Once the OLED in a certain pixel unit, or the driving circuit of the OLED fails, especially suffers from a short circuit, a large current will flow to an undesired position or device. A plurality of pixel units in the periphery of a defective pixel unit may be affected. Therefore, there is a need to provide a protection circuit in a display, especially an OLED display.